The Role of Scattering in Quasi-Ordered Structures for Terahertz Imaging: Local Order Can Increase an Image Quality

Dolganova, Irina N.; Zaytsev, Kirill I.; Yurchenko, Stanislav O.; Karasik, Valeriy E.; Tuchin, Valery V.

doi:10.1109/tthz.2018.2844104

Cited by 22 publications

(11 citation statements)

References 49 publications

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“…THz technologies are still far from clinical application, suffering from a list of problems, such as low performance of THz sources and detectors, and low spatial resolution due to high absorbtion and scattering. 46 , 47 However, the rapid progress of THz sources and optical components in the recent years 48 – 52 stimulates the further improvements of THz instruments for biophotonics. A strong limitation is caused by the absence of efficient waveguides and fibers.…”

Section: Resultsmentioning

confidence: 99%

In situ terahertz monitoring of an ice ball formation during tissue cryosurgery: a feasibility test

et al. 2021

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Significance: Uncontrolled cryoablation of tissues is a strong reason limiting the wide application of cryosurgery and cryotherapy due to the certain risks of unpredicted damaging of healthy tissues. The existing guiding techniques are unable to be applied in situ or provide insufficient spatial resolution. Terahertz (THz) pulsed spectroscopy (TPS) based on sensitivity of THz time-domain signal to changes of tissue properties caused by freezing could form the basis of an instrument for observation of the ice ball formation.Aim: The ability of TPS for in situ monitoring of tissue freezing depth is studied experimentally.Approach: A THz pulsed spectrometer operated in reflection mode and equipped with a cooled sample holder and ex vivo samples of bovine visceral adipose tissue is applied. Signal spectrograms are used to analyze the changes of THz time-domain signals caused by the interface between frozen and unfrozen tissue parts.Results: Experimental observation of TPS signals reflected from freezing tissue demonstrates the feasibility of TPS to detect ice ball formation up to 657-μm depth.Conclusions: TPS could become the promising instrument for in situ control of cryoablation, enabling observation of the freezing front propagation, which could find applications in various fields of oncology, regenerative medicine, and THz biophotonics.

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Section: Resultsmentioning

confidence: 99%

In situ terahertz monitoring of an ice ball formation during tissue cryosurgery: a feasibility test

et al. 2021

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“…So far, THz imaging using various light sources and detectors has been performed, and technologies have been developed as in other wavelength regions [19][20][21][22][23][24]. Among them, time domain spectroscopy (TDS), quantum cascade laser (QCL), and terahertz parametric generator (TPG) using LiNbO 3 non-linear optical crystals have been employed for the imaging at laboratory level below the 3 THz frequency domain.…”

Section: Spectral Imaging Using Thz-felmentioning

confidence: 99%

Spatially Resolved Spectral Imaging by A THz-FEL

et al. 2020

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Using the unique characteristics of the free-electron-laser (FEL), we successfully performed high-sensitivity spectral imaging of different materials in the terahertz (THz) and far-infrared (FIR) domain. THz imaging at various wavelengths was achieved using in situ spectroscopy by means of this wavelength tunable and monochromatic source. In particular, owing to its large intensity and directionality, we could collect high-sensitivity transmission imaging of extremely low-transparency materials and three-dimensional objects in the 3–6 THz range. By accurately identifying the intrinsic absorption wavelength of organic and inorganic materials, we succeeded in the mapping of spatial distribution of individual components. This simple imaging technique using a focusing optics and a raster scan modality has made it possible to set up and carry out fast spectral imaging experiments on different materials in this radiation facility.

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“…For this reason, a tremendous amount of research is dedicated to the enhancement of far-field THz imaging. In addition to digital image reconstruction techniques, [238][239][240] high-resolution THz imaging based on utilizing aperture synthesis, 241 dielectric cube terajet generation, [242][243][244][245][246] solid immersion imaging, [247][248][249][250] confocal THz laser microscope, 251 and wide-aperture spherical lens 252,253 for 3-D and flat diffractive optics 254,255 were proposed.…”

Section: Terahertz Opticsmentioning

confidence: 99%

Survey of terahertz photonics and biophotonics

et al. 2020

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We review the advances of terahertz (THz) science and technology in biophotonics, including related challenges and solutions. The main impediment to THz spectroscopy and imaging in this field is the high absorption of the THz beam in water. Hence, transmission imaging and spectroscopy of thick wet tissue using THz radiation has generally been quite difficult. However, the absorption of THz waves by water molecules is so strong that increasing the power of the THz source can lead to structural and functional changes in tissues, so solutions must go beyond a larger power output. In terms of resolution, THz imaging is superior to ultrasound but inferior to visible light microscopy. Owing to its unique material analysis capabilities, promising diagnosis applications have been demonstrated through THz imaging and spectroscopy. Unfortunately, many applications are limited by beam penetration depth and resolution. Hence, researchers from a wide variety of scientific and technical fields have been actively improving these features through the development of electronic devices and materials. In addition, groundbreaking optical architecture and materials to reduce beam absorption in the optics of a system and generate focused beams with smaller diameters have been proposed. On the software side, image processing techniques to computationally enhance the resolution and quality of THz imaging have been proposed. Data science and machine learning to automate the diagnosis of defects and diseases through processing THz images and spectroscopy data have been proposed. We have reviewed the applications of THz radiation in biophotonics and research achievements toward advancing these applications. A conclusion with a roadmap toward increasing the footprint of the THz technology in biophotonics is also proposed.

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The Role of Scattering in Quasi-Ordered Structures for Terahertz Imaging: Local Order Can Increase an Image Quality

Cited by 22 publications

References 49 publications

In situ terahertz monitoring of an ice ball formation during tissue cryosurgery: a feasibility test

In situ terahertz monitoring of an ice ball formation during tissue cryosurgery: a feasibility test

Spatially Resolved Spectral Imaging by A THz-FEL

Survey of terahertz photonics and biophotonics

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